The goal of this study is to determine the role of pulmonary metabolism of essential fatty acids, e.g., arachidonic acid in the etiology of intra-arterial thrombosis. This study will determine the factors controlling production of prostaglandins and thromboxanes by pulmonary tissue and vascular endothelium; (2) characterize the events which inhibit or promote platelet aggregation in vivo; (3) compare the response of pulmonary artery and pulmonary vein to stimuli which enhance the metabolism of fatty acids in vivo; (4) the mechanism (s) of action of chemical and environmental agents (to be screened) which may stimulate intra-arterial thrombosis; (5) determine the mode of secretion and transport of pulmonary prostaglandins and thromboxanes via capillary endothelium.